Of course I can explain. The second screen is basically just a render texture that's rendering another camera. There are two versions of the terrain mesh, one with an unlit material for the normal camera and one with a colorful standard material for the screen camera, which is why you get the 3d perspective only on that second screen. Then there's just a bunch of post processing effects like bloom on the second camera to make it look nice and different.

I'm probably gonna be posting my source code soon so you can see for yourself!